<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS Pulse Animation Effects</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <div class="pulse">
        <span style="--i: 1"></span>
        <span style="--i: 2"></span>
        <span style="--i: 3"></span>
        <span style="--i: 4"></span>
        <span style="--i: 5"></span>
        <span style="--i: 6"></span>
    </div>
</body>
</html>